1. Field of the Invention:
This invention generally relates to switchgear apparatus and, more particularly, to an improved enclosure structure for housing circuit breaker assemblies.
2. Description of the Prior Art:
Circuit breaker units of the low, medium and high voltage type require a structure or cell of sheet metal which houses and encloses the units for safety purposes and facilitates connection with the bus ducts and other auxiliary equipment. Since the circuit breaker assemblies are inserted into and mounted within such structures or enclosures, it is critical that the enclosures be manufactured in such a way that their physical dimensions meet close tolerance limits. These requirements were met in the prior art by welding the sheet metal parts of the enclosure structure together with the aid of suitable jigs or by using roll-formed parts. Since both methods of manufacture employed sophisticated and expensive tooling that required frequent maintenance, the manufacture of metal enclosures in accordance with the prior art practices was expensive and time consuming.
It would, accordingly, be very advantageous from both a manufacturing and cost standpoint if such metal enclosures and similar structures could be fabricated to the close dimensional tolerance required without the use of roll-formed parts, assembly jigs or welding operations.